When delivering fuel directly to an engine combustion chamber, the fuel must be highly pressurized both to overcome the pressure in the combustion chamber and to assure that the fuel is properly atomized and disbursed in the combustion chamber. In one form of injector proposed for this purpose, a sleeve responsive to combustion chamber pressure cooperates with a stationary piston in the injector to create the high pressure. Before this invention, however, such injectors required complex valve arrangements to permit supply of fuel to the injector and to allow injection at the appropriate time and in an appropriate amount.